Just one thought - you might also also modify the care-unit as well
to remove the available bed.
SDG
jco
co-founder & director Dallas Rules Group
sponsor October Rules Fest business rules conference Oct 22-24 Dallas,
TX
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A small bird will drop frozen dead from a bough
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David Herbert Lawrence.
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On Jul 2, 2008, at 7:51 AM, Peter Lin wrote:
the example confuses me a bit. If I had to do the same thing the rule
might look like this.
(defrule assignBed
?patient <- (patient
(id ?p)
(unit ?u)
(bed ?b&:(eq ?b 0) ) ;; if the patient hasn't been assinged.
assuming unassigned is zero
)
(care-unit
(id ?u) ;; join on the patient's assigned care-unit
(availableBeds ?beds&:(> ?beds 0) ) ;; checks to see if unit
has available bed
)
(bed
(id ?bedid) ;; bind bed id to variable "?bedid"
(unit ?u) ;; join on the care-unit
)
=>
(modify ?patient (bed ?bedid) )
)
The example in the email wouldn't work, since it would only match
patients that are already assigned to a bed in a care unit. I'm
guessing, you only want to assign beds to patients without an assigned
bed. The first pattern checks to make sure it doesn't try to find a
bed for patient that already has one.
doing it this way, the search space should be considerably smaller.
peter
On Wed, Jul 2, 2008 at 8:44 AM, Florian Fischer
<[EMAIL PROTECTED]> wrote:
Hello,
I have a question about optimizing a query in Jess.
I have (let's take round numbers) 100 care units. Each care unit
has 20
beds and on average 10 patients.
I want to match patients to their beds. A patient has an attribute
giving its current bed.
I could write something like
(defrule ...
(bed (id ?b))
(patient (id ?p) (bed ?b))
(not (the patient is attached to the bed))
=>
(attach the patient to the bed)
)
but then, each patient is compared to each bed, which takes 2
millions
comparisons. I'd like to optimize that by first matching a patient
to
its care unit and then comparing the patient with the beds of that
care
unit. That would take 1000*100 tests to match patients to care units
and then 1000*20 tests to find the right bed. That is 120'000
instead
of 2'000'000 comparisons.
So I would write something like this:
(defrule ...
(care-unit (id ?u))
(bed (id ?b) (unit ?u))
(patient (id ?p) (unit ?u) (bed ?b))
(not (the patient is attached to the bed))
=>
(attach the patient to the bed)
)
but will it work? Will the matching of patients to care units be
factored out and then compared only to the beds matching the care
unit,
or will each patient be checked against each of the 20000
intermediates
results of the first 2 lines?
Best regards,
Florian Fischer
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